Support the essential part of Shadow DOM v1

third_party/WebKit/Source/core/editing/Position.cpp

Index: third_party/WebKit/Source/core/editing/Position.cpp
diff --git a/third_party/WebKit/Source/core/editing/Position.cpp b/third_party/WebKit/Source/core/editing/Position.cpp
index 11f4d405afc432170a644f3e5ae4ec9c3052ae5e..2f13c06b17eb26cf2dfe730e56480977ea8e21a9 100644
--- a/third_party/WebKit/Source/core/editing/Position.cpp
+++ b/third_party/WebKit/Source/core/editing/Position.cpp
@@ -393,7 +393,7 @@ PositionInComposedTree toPositionInComposedTree(const Position& pos)
         Node* anchor = pos.anchorNode();
         if (anchor->offsetInCharacters())
             return PositionInComposedTree(anchor, pos.computeOffsetInContainerNode());
-        ASSERT(!isActiveInsertionPoint(*anchor));
+        ASSERT(!anchor->isSlotOrActiveInsertionPoint());
         int offset = pos.computeOffsetInContainerNode();
         Node* child = NodeTraversal::childAt(*anchor, offset);
         if (!child) {
@@ -402,7 +402,7 @@ PositionInComposedTree toPositionInComposedTree(const Position& pos)
             return PositionInComposedTree(anchor, PositionAnchorType::AfterChildren);
         }
         child->updateDistribution();
-        if (isActiveInsertionPoint(*child)) {
+        if (child->isSlotOrActiveInsertionPoint()) {
             if (anchor->isShadowRoot())
                 return PositionInComposedTree(anchor->shadowHost(), offset);
             return PositionInComposedTree(anchor, offset);